1. Field of the Invention
The present invention relates a GPS data recording apparatus and a related method thereof, and particularly relates to a GPS data recording apparatus, which can record and replay GPS data, and a related method thereof.
2. Description of the Prior Art
GPS (Global Positioning System) was established by USA government, which can be roughly classified into three major parts: a universe satellite part, a ground management part and a user receiver part. The universe satellite part is composed of 24 satellites, which are divided into six tracks, operate at a height of 20,200 kilometers, and spend 12 hours to go round the earth. Each satellite transmits wireless radio waves with satellite track data and time to various receivers on the earth. The ground management part is a ground management station for tracking and controlling operations of the above-mentioned satellites. The main duty of the ground management station is to amend and maintain parameter information according to which each satellite can operate correctly, whereby each satellite can provide correct information to a user receiver. A user receiver is used for tracking all GPS satellites, and calculates the coordinates of a receiver's location, moving speed and time. The part of this GPS system that is utilized and owned by the mass population is the user receiver part.
The computing theorem of GPS is as follows. Each satellite has a coordinate (a known value) indicating the location of which at every moment when it operates, and the receiver has an unknown value. The transmission time of a satellite message can be obtained via clocks in the satellite and the receiver. The distance between the satellite and the user receiver can be computed via multiplying the difference between the clocks in the satellite and the receiver with a wave transmission speed (i.e. light speed), whereby a relative equation can be obtained according to trigonometry vector. A receiver utilizes such an algorithm to compute the coordinates of the location thereof. A relative equation can be obtained once signals of a satellite are obtained, and thus a plane coordinate value can be obtained (i.e. longitude and latitude) if signals of at least three satellites are received. If signals of four satellites are received, a height value can be obtained; if signals of more than five satellites are received, the accuracy of the coordinates increases. The above-mentioned description briefly explains the basic positioning rule of GPS, and other detail GPS operation can be obtained via GPS documents provided by GPS manufacturers.
Besides in navigation systems for cars, GPS is gradually being utilized for other electronic products as well, and therefore the measurement and experimenting of GPS data become important issues for each manufacturer. Conventionally, a GPS simulation system is utilized for compiling GPS signal data, but GPS data in the real word is easily affected by various effects and interferences. Additionally, the scope that a GPS simulation system can simulate is limited, and therefore a large difference may exist between real and simulated GPS data.